Jukka the Sling was the leader of a tribe of squirrels native to a pine grove near Salamandastron. She and her tribe, notably the healer Ruro, assisted Fleetscut the hare on his quest to recruit hares to help Salamandastron, despite the fact that many members of the tribe (with the exception of Ruro) greatly disliked him.

Though Jukka and her tribe saved Fleetscut from pursuing vermin, she refused his pleas for help, insisting that there was no way her tribe could dislodge the Blue Hordes. Her position was that there was no benefit to her and her tribe, which--plus the fact that her tribe treated war as a business and only fought if they could scavenge weapons and equipment from the slain vermin afterwards--provoked hostility in Fleetscut, who accused Jukka and her squirrels of cowardice. Jukka took strong exception and for the sake of her pride decided to help Fleetscut find King Bucko Bigbones, who was rumored to have a large army of hares. However, she disliked the hare's righteousness and insulting manner and continually argued with Fleetscut for the duration of the journey, even after she and her squirrels had joined the army of Lord Brocktree.

When the army reached Salamandastron, Jukka disguised herself as a Blue Hordebeast by shaving her tail and dyeing her fur, and conducted spy work inside the mountain. She received quite a bit of valuable information, but her disguise failed when she literally ran into Ungatt Trunn and inadvertently slipped back into her typical, archaic mode of speech. With no alternative, she fled, and encountered Fleetscut in the cellars and they were soon hemmed in by vermin. Though their only weapon was a javelin, the pair held the vermin in the tunnel until the rest of Brocktree's army could arrive. Both, unfortunately, died in the attempt.

Jukka and Fleetscut died as comrades-in-arms, despite their former enmity.